New Features in PHP 8.2: Readonly Classes, DNF Types, Random Extension and Deprecation of Dynamic Properties

The PHP development team announced that PHP 8.2.0 is now immediately available as the latest minor version of the PHP language.

PHP 8.2 introduces many improvements and new features, including:

Readonly classes

Disjunctive Normal Form (DNF) types

New standalone types: null , false , true

New “Random” extension

Constants in traits

Deprecation of dynamic properties

Marking a class as readonly adds a readonly modifier to every declared property and prevents the creation of dynamic properties. It is also impossible to enable them by using the #[AllowDynamicProperties] attribute; attempting to do so triggers a compile‑time error.

<?php
#[AllowDynamicProperties]
readonly class Foo {
}
// Fatal error: Cannot apply #[AllowDynamicProperties] to readonly class Foo
?>

A readonly class can be extended only when the subclass is also declared as readonly.

The creation of dynamic properties is deprecated unless the class explicitly opts‑in with the #[\AllowDynamicProperties] attribute. stdClass still permits dynamic properties. The use of __get() / __set() magic methods is not affected by this change. To resolve deprecation warnings, you can:

Declare properties (preferred).

Add the #[\AllowDynamicProperties] attribute to the class (applies to all subclasses).

If you need to associate extra data with an object you do not own, use WeakMap .

Official changelog: https://www.php.net/ChangeLog-8.php#8.2.0